The purpose of this proposal is to renew the Training Program in Nutritional Metabolism, a highly successful Program to train basic, clinical and translational scientists in nutrition-related research. The goal of the Program is to train researchers in a broad number of related areas, focusing on 8 major areas of particular strength in metabolism and nutrition training across the Harvard Medical Campus. These areas also represent important areas of focus for NICHD, including pediatric nutrition, with emphasis on development and bone health, HIV, Vitamin D metabolism, genomic and metabolomics, epidemiology, obesity and appetite regulation, and nutrient trafficking. The grant draws from a large group of highly successful faculty across Harvard. The training faculty represents a number of Divisions, Schools and specific Programs across the Harvard Medical Campus. The Faculty has a great deal of experience in mentoring and has shown a long-track record of commitment in this regard. Their expertise spans the entire field of nutrition, from basic cell signaling to functional metabolomics and imaging, genomics and GWAS studies, epidemiology and large cohort studies, and detailed physiology investigations, unraveling neuronal signaling on appetite regulation and metabolic pathways of nutrient trafficking and body composition regulation. The outstanding efforts of this faculty have resulted in a significant success, as measured by a number of metrics in the first grant cycle, including numbers of articles published by trainees, academic success in promotion to faculty and procurement of independent grant support. The grant has not only fostered opportunities for individual success, but has encouraged a number of outstanding research collaborations between faculty and trainees, in different but often complementary fields of pediatric nutrition research. In the renewal application, a strong core curriculum in nutrition and a comprehensive mentoring structure will ensure that all Trainees develop a broad foundation in methods of nutrition research as well as an expertise in their chosen area of investigation. Core courses, a didactic curriculum, thrice yearly mentoring group meetings, and annual seminars will ensure program cohesiveness and foster multidisciplinary research collaboration. The proposal seeks to fund 4 slots/year and is led by a well-respected PI, Associate Director, Executive Steering Committee, and a newly added External Advisory Board. The demand for the Program has been very significant during its first cycle. Funds are now requested to renew Program for a second 5 year funding cycle.